<?php
/**
 * Zend Framework
 *
 * LICENSE
 *
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 *
 * @category   Zend
 * @package    Zend_Pdf
 * @subpackage FileParser
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 * @version    $Id: String.php 18993 2009-11-15 17:09:16Z alexander $
 */

/** Zend_Pdf_FileParserDataSource */
require_once 'Zend/Pdf/FileParserDataSource.php';

/**
 * Concrete subclass of {@link Zend_Pdf_FileParserDataSource} that provides an
 * interface to binary strings.
 *
 * @package    Zend_Pdf
 * @subpackage FileParser
 * @copyright  Copyright (c) 2005-2009 Zend Technologies USA Inc. (http://www.zend.com)
 * @license    http://framework.zend.com/license/new-bsd     New BSD License
 */
class Zend_Pdf_FileParserDataSource_String extends Zend_Pdf_FileParserDataSource
{
	/**** Instance Variables ****/


	/**
	 * The string to parse.
	 * @var string
	 */
	protected $_string = '';



	/**** Public Interface ****/


	/* Concrete Class Implementation */

	/**
	 * Object constructor.
	 *
	 * Verifies that the string is not empty.
	 *
	 * @param string $string String to parse.
	 */
	public function __construct($string)
	{
		if (empty($string)) {
			require_once 'Zend/Pdf/Exception.php';
			throw new Zend_Pdf_Exception('String is empty',
			Zend_Pdf_Exception::PARAMETER_VALUE_OUT_OF_RANGE);
		}
		$this->_size = strlen($string);
		$this->_string = $string;
	}

	/**
	 * Object destructor.
	 */
	public function __destruct()
	{
		$this->_string = '';
	}

	/**
	 * Returns the specified number of raw bytes from the string at the byte
	 * offset of the current read position.
	 *
	 * Advances the read position by the number of bytes read.
	 *
	 * Throws an exception if there is insufficient data to completely fulfill
	 * the request.
	 *
	 * @param integer $byteCount Number of bytes to read.
	 * @return string
	 * @throws Zend_Pdf_Exception
	 */
	public function readBytes($byteCount)
	{
		if (($this->_offset + $byteCount) > $this->_size) {
			require_once 'Zend/Pdf/Exception.php';
			throw new Zend_Pdf_Exception("Insufficient data to read $byteCount bytes",
			Zend_Pdf_Exception::INSUFFICIENT_DATA);
		}
		$bytes = substr($this->_string, $this->_offset, $byteCount);
		$this->_offset += $byteCount;
		return $bytes;
	}

	/**
	 * Returns the entire string.
	 *
	 * Preserves the current read position.
	 *
	 * @return string
	 */
	public function readAllBytes()
	{
		return $this->_string;
	}


	/* Object Magic Methods */

	/**
	 * Returns a string containing the parsed string's length.
	 *
	 * @return string
	 */
	public function __toString()
	{
		return "String ($this->_size bytes)";
	}
}
